> It sounds like her clients backing out last minute is evidence of poor performance, even if the sales were entirely managed properly before that.

Certainly not without more details.

Good sales is far more complicated than closing deals. It's like in poker: you'd much rather fold a good hand (unclose a good deal) than shove all in and then lose to an even better hand (close the deal and then discover the customer was a bad fit, which has negative second- and third-order consequences.)